Well these past few months have been busy, my wife is pregnant and were having a boy in September. I just wanted to touch on a few tips and pointers for pond construction today.
When digging your pond you should select a naturally low area that can help with natural drainage to your new pond, when you start digging you need to take the first few feet or however much natural topsoil you have on the location of the pond and set it aside for dressing the area around the pond after the excavation is complete.
When you do get that out of the way and you get to the clay you should determine if it will be adequate to seal your pond. There are many methods everyone has an opinion, I personally take a hand full and ball it up tight and see how much of a ribbon it will make when pushed out between your thumb and index finger. If you get a two or so inch ribbon before it breaks off and falls to the ground, you should be ok if you line your pond with the clay you have on site.
When you have your pond excavated to your desired shape and or depth do leave at least 12 inches of undercut to allow for the clay to be spread and walked in or compacted how ever your prefer and feel comfortable with at least 2 feet above the desired water level tapering off into the natural ground. When this is done you can take into consideration the area for your over flow and use a spillway design or an over flow pipe depending on your preference and budget or needs.
When you choose the overflow you should make all swales and available drainage able to flow into the pond or away depending on preferences. When this is complete you can the take the top soil and spread it at 4 to 6 inches depths depending on how much you have and your are ready to seed sod or sprig which I recommend at least one of the methods to ensure and slow erosion and silt and sediment build up into your new pond.
If the pond is desired for fishing you can have logs, stumps, concrete pipes and many other things to give your new pond a good habitat for the fish. Also leaving shelfs and or shallow area 5 or so feet in depth below the water level also will give the fish a spawning area so you have a healthy eco-fishery for many years to come. A fountain or aerator will also help your fish grow faster and be hearty and healthy. These are all opinions I have from my many years of pond excavation and as stated everyone has their preferred methods. If you hire me to excavate a pond please don't insult my 25 years of knowledge by becoming a Google pond expert overnight. I am as honest as they come and will not lie to you about your pond or any matter that may arise.